describe('Array',()=>{
  describe('#indexOf()',()=>{
    it('should return -1 when the value is not present',()=>{
      assert.equal(-1,[1,2,3].indexOf(4));
    });
  });
  describe('#indexOf2()',()=>{
    it('should return -1 when the value is not present',()=>{
      assert.equal(-12,[1,2,3].indexOf(4));
    });
  });
});